Telephone exchange system



May 31, 1932. Rj STOKELY l m6111515 TELEPHONE EXCHANGE SYSTEM Filed Oct. l, 1930 Wwf /Nl/E/VTOR Rummy Patented May` 31:n $932' l UNITED i STATES.

PATENT ortica i my L. sroxnmr, or store-AL maar.A Yoan, Assieuoerro Brat rELErHoNfE Barcares, macaroni/iran. omrnw .roam N. Y., A ooeroearroir or New Yoan I TELEPHONE EXCHANGE SYSTEM Application led October 1,

automatic switches are provided for estab-y l ll;

lishing connections` l The object of this invention is to improve the construction of line-finder switches andl to render their operation more positive and reliable. A l n In telephone systems now'inuse two-motion step-by-step automatic switches having two ysets of brushes are employed as linefinders for extending calling lines to idle iirst selectors. The lines terminating lin thebanks of such a line-Finder are divided into groups, one groupfor each level. Each group is divided into two sub-groups, the lines in one other set of brushes. In order that the action sub-group being accessible to the one set of brushes and the lines in the othersub-group being accessible to the other set of brushes.

1.? Upon the origination of acall over one of the lines,iboth setsk of brushes are advanced in a primary movement' to the level in which the terminals of the calling line are located; thereafter the brushes are advanced in a l secondary movement into engagement with the terminals of thefcallingline. It is necessary that the set of brushes through which connection with the calling line is established be rendered. effective to the exclusion ot the of thetinder be more positive when the terminals of the calling line are reached it 1s de.-

sirable that brush selection be completed pri.-

or toy the secondary movement of the switch.

According to this invention7 a two-motion line-finder switchhavingtwo setsy of brushes is alsorprovided with two commutatore, one for use in selecting1 the group of terminals whichthe terminals oi the calling line 4are lo.-

"" cated, and they other for indicating the sub group and for rendering the set of brushes having access rthereto effective to the .exclusion of the .other set of brushes'. l

Another feature of this invention a lin finder .switch havingr twosets of brushes Vand 1930. semi No. 485,642.

two commutatore, one. for use in seleotinothe groupot terminals in which the terminals ofthe calling lineare located and the other for cooperating with a group relay, which is Common .to the two sub-groups in the calling leveLto ina-ke brush selectionas soon rasthfe level of the calling'line is reached.; f

The invention is4 illustrated in a system using step-byfstep line-finder switches each having a. capacity of 200 lines; but the inven-I tion is applicable to any iinder switch In such a system the subscribers lines are. divided into groups of 200 lines, the lines of each group being connected to terminals in the banks of a corresponding group of linefnder switches, n One set of brushes of each linefinder switch has access to the terminals of one'half of the linesy of a group,and another set of brushes has accessto Vthe termi.- na-ls of. the other half of the group. Each line is provided with the usual line and cut-Y oit relays, and a start relay (also known as a group relay) is provided for every 2O lines to which both sets of brushes have access on one level. Upon origination of a call at any station the operation of' the corresponding line and start relay causes an idle linesinder switch to hunt for the terminals of the call finder is arranged to transfer its line conductors from one seti of brushes to the other, de'

pending upon in which kofthe two subgroups the terminals of the ycallingfline are located. f

The drawing discloses a lineffinder switch embodying the features .of this invention and also illustrates in diagrammatic manner a iirst selector switch :with which the lineinder is permanently associated.

equipped with two sets of brushes and banks. l

Referring tothe drawing, A and 13 repre Y sent-subscribers stations connected, by .the lines l land 1.01, respectivelmto terminals in I" the terminals in bank 30.

the banks of aI group of line-finder switches, of Which one only is shown. This line-inder LF has two sets of brushes, mounted on one shaft and designated 21, 22 and 23 and 31, 32 and 33, respectively. The brushes 21 and 22 have access to the terminal bank 20, the brushes 31 and 32 have access to the bank 30, and the brushes 23 and 39 have access to the bank 40. Each bank has 100 sets of termil nals arranged in ten levels, ten pairs of terminals per level. The two terminals of each pair are separated vertically the same amount as the corresponding pair of brushes, so that both brushes of a pair make contact simultaneously With both terminals of a set in any position. A brush-switching relay 24 controls the connections from the tivo sets of brushes so that only 'the brushes 21, 22 and 23 are operatively effective when relay 24 is normal, and only the brushes 31, 32 and 33 are operatively effective When relay 24 is operated. A yvertical magnet 13 is provided for advancing the shaft and brushes one step at a time in a vertical direction; and a ro f? tary magnet 1T is provided for rotating the shaft and brushes one step at a time over the terminals in any selected level. A release magnet 26 is provided for releasing the shaft so that the brushes may be returned to their i normal position.

The conductors of 100 lines,"including the line 1, are connected to the terminals in bank 20; and the conductors of another 100 linesincluding the line 101, are connected to The associated test or sleeve conductors of these lines are connected to the correspondingly located terminals in the bank 40. Thus line 1 is shown connected to terminals in the second level of 1 bank 20, line 101 is shown connected to terminuls in the. second level of the bank 30, the sleeve conductor 4 et line 1 is connected to the lower terminal. of the pair which is located in the corresponding position of the -i second level of bank 40, and the sleeve conductor 104 of line 101 is connected to the upper terminal of this pair in bank 40. The

start (group) relay is associated withy all of the lines connected to the second and it is operated Whenever the origination of a call over any Lof these lines causes the operation of the corresponding line relay. The operation of relay 6, ork of any of the other start (group) relays associated with lines connected. to banks or 30, connects ground to start conductor 8 which leads successively through all the busy linefinders ofthe associated group to the start relayof the Vfirst idlefinder.y

The switch LF also includes two commutators 14 and 15,'each of which has one seg'- ment with which the corresponding commutator brush is normally in contact and ten if; off-normal segments, one for each level of the terminal banks.V The brushes are attached to the shaft so that they make contact successively with each of the off-normal commutator segments during the vertical movement ot the switch. Ground is normally connected to each of the ten off-normal segments of commutator 14, but the operation of any one of the ten start relays disconnects the ground from the corresponding segment so as to stop the vertical movement of the switch when the multiple brushes have been raised tothe level in which the terminals of the calling line are located. Commutator 15 is used to control the operation of brush-switching relay 24, the segments of this commut-ator being normally connected neither to battery nor to ground. Whenever a call is originated over a line connected to terminals of bank 30, the operation of the start (group) relay connects ground to the corresponding off-normal segment of commutator 15 so as to operate relay 24 when the multiple brushes have been raised to the calling level. The rotary magnet 17 is then'efective to rotate the brushes successively fromone set of terminals to the next until the terminals of the calling line are reached.

To describe the operation in detail assume that the subscriber at station A initiates a call. When the receiver is removed from the receiver hook at station A the line relay 2 operates in an obvious circuit. Relay 2 closes a circuit for operating roup relay 6 and the Winding of cut-olf re a 3 is connected through the right-hand liont contact of relay 2, over conductor 4, to the sleeve terminal of the line 1 in bank 40. Relay 6 disconnects ground from conductor 7 so as to mark the second commutator segment of all of the linefmders having access to the line 1, and connects ground to start conductor 8. Assuming theline-inder LF to be the first idle finder in the group, the ground on conductor 8 is extendedl through the outer right-hand back Contact of relay 19 to the Winding of relay 10. Relay 10 operates thereby closing a circuit for energizing relays 11 and 12. The circuit for operating` relay 12 may be traced from battery through its Winding, through the brush and normal segment of commutator .14, to ground at the left-hand front contact of rela-y 10. The circuit for energizing relay 11 may be'traced from battery throughresistance 29, the left-hand back contact oi relay 19, through the normally closed contacts of rotary magnet 17, winding of relay 11, back contact of the vertical maginet 13, and through the rleft-hand back contact of relay l2, to ground at the left-hand frontcontact of relay 10.r When relay 12 operates thefcircuit for operating relay 11 is traced through the left-hand front contact of relay 12 (instead of through its back contact) and thence through the brush and normal segment of commutator 14, to ground i at the the left-hand front contact of relay 10. Relay 11 is locked operated through its front contacts, independent of relay 12 and independent of the-commutator 14; `and relay 12 is locked'operated through its lefthand front contact and the front contacts of relay 11, tothe ground at the left-hand front contact of relay '10.

With both relays 11 and 12 operated, a circuit is closed .for operating the vertical magnet 13; this circuit is traced from lbattery through its Winding, the right-hand front Contact of relay12, land the outer left hand Jfront contact of'relay 11, to ground at relay '10. The operation of vertical magnet 13 raises the'shaft and all multiple and commutator brushesl up to the iirst level, andv opens the circuit throughv the Winding of Vrelay 11. When relay 11 releases, itopens the circuit through the vvvindingof magnet 13, thereby causing the release of magnet 13. If the terminals ofthe calling `line were located in the iirst level of the terminal bank, relayy 12 would release as soonas its locking circuit is opened by the release of relay 11, the operating circuit for relay 12 having been opened when the brush of commutator 14 Was advanced from its normal position.k yBut in the case here under consideration the terminals of thecalling line are not located inV the iirst level, and relay 12 is held operated through the brush andy iirst'se'gment of commutator 14, to ground at the back Contact of the group relay associated with the lines Which do connect to terminals in the yiirst` level. Relay 11 is then reoperated through vthe left-hand frontfcontact of relay 12, to

ground on the first olf-normal segment of commutator 14. When relay 11 reoperates, a circuit is again closedfor energizing the vertical lmagnet 13; and the reoperation oiY magnet 13 steps the shaft and brushes up to the second level. lVith magnet 13 operated, relay `11 again releases, thereby opening the circuit through the Winding of magnet 13 and again opening the locking circuit of relay 12. Since t-he ground normallyconnected to the second segment'of commutator 14 has been disconnectedtherefrom bythe operation of relay 6, 'relay 12 releases to prevent the further operation of magnet 13.

' VThe calling line being connected to bank 30,

to Which brushes 21 and 22 have access, it is not necessary to operate the brush switching relay 24; and' since relay '6 was o-perated through itslet-hand Winding, no ground is Y connected to conductor 9 to cause the oper-k ation of relay 24. f

' As soon as the shaft was lmoved upward from its normal positiomthe vertical'oi-nor! mal springs 16 were operated to connect ground to conductor 27 and to prepare for the operation of the rotary'magnet 17 The release of relay-i12, after the brushes have been advanced to the calling level, again closes aj Vrelay 11 through the front contacts of magnet 17, the vlower Winding of` relay 18, and through the youter upper back contact oferelay 24 to the. test brush 23. If the calling line is connected to the first set of terminals, set of terminals inthe selected level, relayll ris extended through brush 23, over the sleeve yconductor of the calling line, through the front contact of the operated line relay, and through the Winding of the cut-off relay to battery, thereby Hholding relay 11 operated to prevent the further advance of the brushes...y It the calling line is connected to some other set of terminals in theselected level, relay 11 is not held operated and the release of relay 11 causes the release of magnet 17. When magnet 17 releases,relay 11 reoperates; and thereoperation of relay 11 causesthe reoperation of magnet 17. Relay 11 and magnet 17 are in this manner alternately operated and released until the test brush 23 reaches the sleeve terminal towhich conductor 4 is connected, at which time relay 11 is held operated in series With the Winding of cut-oil relay 3. Thel cut-off relay 3 operates and relay 18 is suiticiently energized by the current through its ylower Winding to close 'a locking circuit ,from battery through its upper Winding and middle upper front contact, through the front contact of magnet 17, the Winding of relay 11, the back contact of magnet 13, and

through the front contacts of relay 11, to ground at the left-hand front contact of relay 10. Relay 18 isnoiv completely operated. to extend the connections from line 1 through brushes 21 and 22, the outer back contacts of relay 24, and the outer front contacts of relay 18, over conductors 51 and 52, to the Windings of ,the line relay 54 of the associatedv selector S. Relay 18 also closes a circuit for operating relay 19, from battery through the left-hand Winding of relay 19 and the inner lower front Contact of relay 18, to the oli?- normal ground on conductor 27. i

When the line relay 54 of selector S operates in thecircuit .over the lcalling line, it closes la circuit for operating relay 55. Re? lay 55 connects'ground over the sleeve -conductor 53, through the inner left-hand front l' contacter' relay 19, the middle and inner upper front contacts ofrelay 18, and the outer upper hacky contact of relay 24 to sleeve brush 23,.thereby holding cut-ofi' relay 3 operated until the connection is released by the calling subscriber. The ground on conductor 5f, is also extended through the left-hand front contact of relay 19 and the middle upper front Contact of relay 18 to hold relay V18 operated until the connection is released, the

lower winding of relay 18 being short-circuited by its own inner and middle upper -front contacts.

lVith the holding ground connected to conduct-or 53, the Winding of relay 11 is shortcircuitcd to cause the release of relay 11; and the release of relay 11 opens the circuit through magnet 17. Relay ll cannot reopcrate` since the circuit for operating this relay islield open at the lett-hand back contact of relay 19. Relay 19 is held operated as long as the off-normal ground is connected to conductor 27. With relay 19 operated, the starting conductor 8 is disconnected from the winding of relay and extended through the outer right-hand front contact of relay 19, over conductor 28 to the next line-finder in the group. Relay 10 releases and relay 19 is now held operated independently of relay 18 by the circuit from battery through the left-hand winding ot relay 19, through the back contact of relay 10, to the off-normal ground on conductor 27.

When operated. the cut-oil1 relay 3 locks through its own front contact independentlv ot line relay 2. and disconnects the conductors of line 1 from the winding of line relay 2. Relay 2 releases thus disconnecting the ground at its left-hand front contact from conductor 5. Group relay 6 releases unless the origination ot a call over one of the other lines associated with this relay hasV caused ground 'to be connected to conductor 5. lVhen relay 6 releases, it rcconnects ground over conductor 7 to the second off-normal segment ot commutator 14 and disconnects the ground at its lett-hand front contact from start conductor 8.

No further operation takes place in the line finder circuit until the connection is released by the calling subscriber at which time the selector switches and connector switch through'which the connection is completed to a called line are restored to normal and lf the holding ground is disconnected from the at station A. Relay 18 also releases when the holding ground is disconnected from conductor 53, thereby closing a circuit for operating the release magnet 26; this circuit 1s traced from battery through its Winding, lower front Contact of the VON springs 16,

lower back contact of relay 18, and through the back contact ot relay 10 to ground on conductor 27. When the shaft and brushes reach their normal position, the ground at the VON springs 16 is disconnected from conductor 27 thereby releasing release magnet 26 and o n-y ing the circuit through the left-hand win in of relay 19. Relay 19 releases unless it is hel operated by a circuit through its right-hand winding and front contact over start conductor 8 to ground at the start (group) relay ot' some other line which has originated a call. As soon as the start conductor 8 is no longer connected to ground, relay 19 releases thereby reconnecting start conductor 8 f through its right-hand back contact to the winding of relay 10 in readiness for thenext call.

When a call is originated at station B, line relay 102 operates to cause the operation of group relay 6 and to connect the winding of cut-off `relay y103 over conduct-or 104 to the sleeve terminal of this line in bank 40. Group relay 6 now disconnects ground from the second off-normal segment of commutator 14, connects ground to start conductor 8 and also extends the ground at the left-hand front contact of line relay 102, through the right-hand Yfront contact of relay 6, over conductor 9 to the second oil-normal se ent of commuta` tor 15. The operation o the line-finder LF in searching for the calling line is now the same as that described when a call is originated at' station A, except that the switching relay 24 is operated as soon as the brushes have been advanced to the second level. The circuit for operating relay 24 is traced from battery through its winding, brush and sec-L ond off-normal segment of commutator 15, and through the righthand front contact of relay 6 to ground at the left-hand front contact of relay 102. The switching relay 24 locks through its inner lower front contact over conductor 27 to the olf-normal ground at the VON springs 16. With rela-y 24 operated, brushes 31, 32 and 33 are rendered operatively effective to the exclusion of brushes 21, 22 and 23. Relay 24 holds until the connection is released and the off-normal ground is disconnected from conductor 27.

Incase the shaft and brushes are stepped around to thetenth set of terminals in any level without finding the calling line, an additional step is taken thereby closing the contacts of the 11th rotary step springs 25.

Relay 18 is thereby operated through its upper winding even though the calling line has not been found. The operation of relay 18 closes the circuit for operating relay 19 thereby extending the starting conductor 8 to the next line-finder in the group. Relay 10 is a primary movement to select one of said termjnal groups, means including a second commutator and elective at the end of the primary movement to select one of said brush sets, and means for advancing said brush sets in a secondary movement into engagement with the terminals of the selected group.

2;., In combination, an automatic switch having two sets of brushes and terminal banks, a relay for switching from' one set of brushes to the other, groups of terminals in each bank so arranged that both sets of brushes simultaneously engage the terminals of a pair of said groups, a start relay for each of said pairs of groups, means effective in consequence of theoperation of any one of said start relays for advancing said brushes in a primary movement, a circuit opened when said brushes reach the pair of groups corresponding to the operated one of said start relays to stop the primary movement, another circuit controlled in part by said one of said start relays and effective as soon as said brushes reach the corresponding pair of said groups for operating said switching relay, and means for advancing said brushes in a secondary movement into engagement with the terminals insaid corresponding pair of groups to select one of the sets of terminals.

3. In a telephone system, an automatic switch having two sets of brushes and termic nal banks, a relay for switching from one set of brushes to the other, groups of lines each divided into two subgroups, the lines of one subgroup being accessible to one of said sets of brushes and the lines of the other subgroup being accessible to the other of said sets of brushes, group relays one for each of said groups of lines, means including one of said group relays effective upon the orgination of a call over one of the lines of the associated group for marking this group, means including a magnet for advancing both-sets of brushes, a circuit closed when said brushes reach said marked group to stop the advance of said brushes, and a circuit closed when said brushes reach said marked group for operating said switching relay.

4. In combination, a two-motion automatic switch having two sets of brushes and terminal banks, a relay for switching from one set of brushes to the other, groups of lines each group 'comprising two subgroups, the lines of one subgroup being connected to terminals in one of said banks and the lines of the other subgroup being connected to the correspondingly located terminals in the other oi' said banks, group relays one for each of said groups of lines, means eective upon the operation `of one of said group relays for advancing the brushes in a primary movement to select the corresponding subgroup, a circuit opened when said brushes reach said corresponding subgroup to stop the primary movement, a second circuit effective as soon as the brushes' reach said lcorresponding subgroupto operate said switching relay, and means for advancingsaid brush sets into engagement with the terminals of the selected group.

5. In a telephone system, a two-motion linefinderA switch having two sets ot brushes, groups of terminals in the bank oi'said switch, each group divided into two sub-groups, re- 'iays one for each of said Groups of terminals, subscribers lines connected to the terminals of said bank, means including .one of Vsaid group relays and effective upon the orgination of a call over one of said lines for starting the operation oi' said switch, means including a commutator for advancing the brushes of said switch in a primary movement to the group which includes the terminalsfo't the calling line, means for advancing Vsaid brushes in a secondary movement into contact with the terminals of said selected` 6. In a telephone system, a finder switchA comprising two sets of terminal banks and corresponding sets of brushes, groups of lines connected to the terminals in said banks so that one oi said sets of brushes has access to half the lines in each group and the other of said sets of brushes has access to the other half of said lines in each group, a relay for switching from one set of brushes to the other, group relays one for each of said lgroups of lines, means eii'ective upon the operation of any one of said group relays for advancing the brushes in a primary movement, a circuit opened when the brushes reach the group corresponding to said one oi the group relays to stop the primary movement, a circuit closed when said brushes reach said corresponding group for operating said switching relay, and means for advancing said brushes in a secondary movement to select one of the sets of terminals in said corresponding group 7 In a telephone system, a two-motion finder switch comprising two sets of terminal banks and corresponding sets of brushes,

groups of lines connected to the terminals in said banks so that one set of brushes has access to half of the lines in each group and the other of said brushes has access to the other half of said lines in each group, a relay for switching from one set of brushes to the other, group relays one for each of said groups of Y lines, two commutators having segments corresponding to each of said groups, means eiiective upon the origination of a call over anyone of said lines for operating the corresponding one of said group relays to mark the corresponding segment of one of said commutators, means for advancing said brushes in a primary movement to said marked group, means including the corresponding segment of the other of said eommutators effective if said one of said group relays is operated in consequence of the origination of a call over a line to which one of said sets of brushes has access and ine'ective if said one of said group relays is operated in consequence of the origination of a call over a.

Fi i

line to which the other of said sets of brushes has access for operating said brush switching relay, and means for advancing said brushes in a. secondary movement to select the set of terminals to which the calling line is connected.

In witness whereof, I hereunto subscribe my name this 30th day of September, 1930. RAY L. STOKELY. 

